Disk drive head suspension assemblies with so-called second stage actuators or microactuators often include piezoelectric motors that are attached to the suspensions to effect movements of the suspension assemblies and components. The piezoelectric motor acts as an actuator and is controlled by electrical and electronic control circuitry that supplies electrical signals to excite the piezoelectric motor and cause the motor to create desired movement of the suspension. The control circuitry is electrically connected to terminals on the piezoelectric motors through flex circuit-type connectors or leads.
Known suspension assemblies have employed wire bonding to connect the flex circuit leads to the terminals of the piezoelectric motors. In the wire bonding process, a terminal on the flex circuit connector is electrically and mechanically attached to a terminal on the piezoelectric motor by ultrasonically welding. However, the ultrasonic welding process has some drawbacks. For example, it can be difficult to effectively achieve a robust electrical connection when wire bonding on the piezoelectric motor. In addition, the vibration created by the ultrasonic welding process can damage the piezoelectric motor, especially the terminal, which typically includes a thin layer of gold, or cause a protective encapsulment material that is applied to the surface of the motor to flake off, potentially compromising the integrity of the motor. Further, the wire bonding process is typically limited to bonding in a linear path. That is, multiple attachments can occur only along a horizontal or vertical line, but not both, without additional process steps.
Another known process includes applying solder to attach the connector to the motor terminal. In this process, a solder bump is applied to the connector and allowed to harden before the connector is positioned adjacent the terminal. The connector is positioned with the solder bump contacting the termination area of the motor so that the solder bump is not directly accessible from an outside surface of the assembly. Then, a holding member is positioned to engage with and apply a spring loaded force against the connector and motor to hold the connector in close proximity to the terminal. The connector is then heated via a heat source applied directly onto the connector. The heat radiates through the connector to the solder until the solder changes to a molten state or “reflows.” In the case of a multi-layered connector, heat is applied to an outer layer of the connector. The heat then radiates through the layers of the connector to the solder to reflow it. Once the solder has reflowed, the heat is removed until the solder cools and solidifies to create an electrical and mechanical bond between the terminal and the connector. The holding member continues to apply the spring loaded force after the heat is removed and until the solder has cooled and solidified. The resultant heat, which will also radiate through to the piezoelectric motor, along with the applied spring loaded force, can damage the piezoelectric motor or distort other suspension assembly components. Furthermore, applying solder to the terminal, positioning the connector adjacent the terminal, and heating the assembly to cause the solder to reflow creates added steps in the attachment process.
What is desired is an improved process to attach a connector to the terminal of the piezoelectric motor that can be done efficiently and with relatively little potential for damaging piezoelectric motors. A method that applies minimal force, uses relatively low temperatures or localized heating, and is capable of being performed at very high speed would be especially desirable.